National Science Council

National Taiwan University

Tung Nan Institute of Technology

Guan-Chyun Hsieh

Chang-Hua Lin

Wei-Li Hsu

Hung-Liang Chen

Jui-Chih Cheng

Cheng-Yuan Tsai

Chang-Huan Liu

The present invention provides a resonant converter with a synchronous rectification drive circuit. The resonant converter with the synchronous rectification drive circuit includes a switch circuit, a resonant circuit, a transformer, a full-wave-rectifier circuit and a synchronous rectification drive circuit, wherein the switch circuit at least includes a half-bridge circuit, the resonant circuit is coupled to the switch circuit and has a resonant frequency, the transformer has a primary side coupled to the resonant circuit, the full-wave-rectifier circuit is coupled to a secondary side of the transformer and includes two switches, the synchronous rectification drive circuit includes four voltage-clamped drive circuits having output terminals coupled to the switch circuit and the corresponding switch of the full-wave-rectifier circuit, and each voltage-clamped drive circuit includes a transmission/discharge circuit for reducing the turn-off period of the coupled switch during turning off the coupled switch.

Resonant converter with synchronous rectification drive circuit

A Synchronous PWM controller realized by dead-time modulation is provided for applying to the self-oscillation Royer inverter. The proposed dead-time-modulated PWM (DTM-PWM) controller is composed of a monostable circuit and a constant-current charger (CCC). The presented switching period for the buck regulation consists of a referred sawtooth having a constant-period and a dead-time. The synchronizing strategy is conducted by modulating the dead-time according to the resonant frequency of the Royer inverter. Two kinds of the control strategies in DTM-PWM controller are explored including the down-going and up-going error voltage controls. A DTM-PWM controlled dimmable Royer inverter with two-CCFL having primary-side control is designed and realized. Two kinds of the existing controllers for the Royer inverter are also experimented and compared with the proposed DTM-PWM controller. The results of the analysis and the theoretical prediction are verified with the experiments.

Dead-time-modulated synchronous PWM controller for dimmable CCFL royer inverter

An inverter for converting a DC input voltage into an AC output voltage using the sigma-delta modulation (SDM) is provided which includes: a SDM controller for producing a modulated output voltage signal according to a reference voltage signal, a driving circuit electrically connected to the SDM controller for producing a driving signal according to the modulated output voltage signal, and a power inversion stage circuit electrically connected to the driving circuit for producing the AC output voltage according to the driving signal. A controller for producing a modulated output voltage signal according to a reference voltage signal is also provided which includes: an integrator circuit, a sample-and-hold circuit electrically connected to the integrator circuit, and a quantizer circuit electrically connected to the sample-and-hold circuit and electrically connected to an input terminal of the integrator circuit through an output terminal thereof.

Sigma-delta modulation inverter with programmable waveform output

A generator is used in a controllable dimmer ballast of a fluorescent lamp for eliminating a striation. The generator includes an interface for transforming an input signal to a first input voltage and a second input voltage, an oscillator electrically connected to the interface for receiving the first input voltage and producing a pair of complementary pulse trains, a comparator electrically connected to the interface for receiving and comparing the second input voltage with a given threshold voltage and providing an enable signal, and a controller electrically connected to the oscillator and the comparator for alternately modulating the pulse trains and providing a first and a second control signals according to the pulse trains and the enable signal so as to eliminate the striation of the lamp.

Apparatus and method for eliminating striation of fluorescent lamp with dimming control

A technology for eliminating acoustic resonance in a fluorescent lamp is disclosed in the present invention. The feature of the invention is to provide a harmonic compensating device to work with the fluorescent lamp and its relative peripheral circuits, such that current-dependent sources are provided to modulate the current in the lamp, thereby spreading the harmonic energy of the current in the lamp and eliminating acoustic resonance.

Harmonized strategy for eliminating acoustic resonance in a fluorescent

A frequency-locked stepping position control servo (FLSPS) system for driving a stepping motor. It essentially comprises a means for driving the stepping motor to move an object toward a target according to a driving signal, a means for detecting position of the object, a position-to-frequency converter to feedback the position information and a microprocessor-based slope-varied frequency-controlled oscillator (.mu.P-SVFCO) to generate the driving frequency. The .mu.P-SVFCO includes a microprocessor to ease the implementation of the control law and utilizes the slope-varied technique to adaptively pump the pulse train frequency of the driving signal. In addition, a one-bit clock is provided to dynamically maintain the position of the object when the target position is reached. The FLSPS system is capable of achieving similar system acquisition times for different target commands among a wide-range of positioning control commands.

Frequency-locked stepping position control system

A series resonant DC-to-AC inverter. This inverter comprises a series-resonant circuit including a resonant capacitor and a resonant inductor, a diode parallel with the series resonant circuit, a switch device controlling the conduction condition between the series resonant circuit and a DC voltage, a cycloconverter and an output filter. The switch device is controlled by a pulse-width-modulated signal. During three operation stages of charging, resonance and discharging, an unipolar composite sinusoidal signal is formed at the resonant capacitor. The cycloconverter transforms the unipolar composite sinusoidal signal into a bipolar composite sinusoidal signal and then the output filter filters out its high-frequency components to generate an AC voltage.

Series resonant DC-to-AC inverter system

A speed controller is equipped to a step motor for controlling the rotation of the step motor with a desired angular velocity. The step motor speed controller utilizes a phase-locked stepping servomechanism (PLSS) in which a phase-controlled oscillator (PCO) comprised of an adaptive digital-pumped controller (ADPC) and a voltage-controller oscillator (VCO) is employed. The step motor speed controller utilizes a tachometer comprised of an optical encoder for detecting the angular speed of the step motor. The tachometer sends out a first pulse train with the frequency thereof indicating the angular velocity of the step motor as a feedback signal to the ADPC. A reference signal source is employed for sending a second pulse train to the ADPC. The ADPC compares the phase difference between the first pulse train and the second pulse train and whereby a signal corresponding the phase difference is sent to the VCO, causing the VCO to output a third pulse train to the step motor. The generated third pulse is thus used to drive the step motor.

Growing community of inventors

Taipei, Taiwan

Guan-Chyun Hsieh